The Blues didn't pack it in dramatically or suddenly. They just dropped away enough to let the Crusaders find their composure and play in the right areas. And it became cyclical.
The more confidence the Crusaders took, the more the Blues lost and the home side's accuracy and cohesion slipped.
The Blues lost some of their accuracy and couldn't get going forward any more and the Crusaders realised they were back in it and simply had to be patient - wait for the Blues to turn the ball over, hoof it down the other end and inevitably a chance to go for goal would present itself.
It felt a little limp in the end, that the Blues just drifted out of the game without really knowing how to stop themselves. And that slow demise from a position of promise made it hard to appreciate that for 50 minutes - maybe longer - the Blues were a real chance.
Defensively, the Blues were unrecognisable from the team they were last week; from the team they have been for much of the season. For all the improvements that have been made since Tana Umaga arrived as coach, the one area that's been slow to evolve is their defensive work.
Rebuilding their structures and confidence is a long-haul job because it was all fairly chaotic last year. The players are having to not only learn a new system, they are also having to learn to trust one another and finally there were signs that it's all coming together.
The Crusaders, by the end of the first half, had been forced to regress to their old ways of attacking side to side. When they have been at their best this season, they have been direct and decisive. They wanted to be like that at Eden Park, but couldn't get on the front foot.
They couldn't punch forward the way they wanted and, when they went wide, couldn't force the Blues to make mistakes.
Because the space didn't open up, the Crusaders resorted to just drifting from one side of the field to the other and, inevitably, became frustrated with their lack of progress and took unnecessary risks to try to break the pattern.
No one better epitomised the improved defensive effort than giant prop Charlie Faumuina who, with quite incredible athleticism, power and agility, scurried from a ruck to hit Johnny McNicholl in a thunderous full-on tackle. The little wing went down hard, took a full minute to get up and then came off with a damaged shoulder.
But without being able to hold that defensive form for 80 minutes, the Blues couldn't hold out and now their season is possibly over in terms of being a playoff chance, or at least definitely no longer is their destiny in their hands.
Blues 21 (I. West, G. Moala tries; I. West con, 3 pens) Crusaders 26 (N. Nadolo, A. Ellis tries; R. Mo'unga 2 cons, 4 pens). HT 15-10